In a continuation of studies in rats and pigs malnourished during early postnatal life it is proposed to examine endocrine function both during malnutrition and after nutritional rehabilitation. Growth hormone, ACTH, insulin, corticosterone, cortisol, T3 and T4 thyroid hormones will be examined. Similar studies will be carried out in which malnutrition is imposed only during gestation in pigs. These hormone measurements will be correlated with behavioral characteristics. Studies of the effectiveness of environmental enrichment introduced at various time periods from birth to 6 months of age on various measurements of latent learning will be made in rats. Rats representing the second generation after malnourishment and rehabilitation will be studied for behavioral and energy and nitrogen utilization during postweaning growth and after growth has plateaued. Energy and dietary nitrogen studies in previously malnourished rats will be continued utilizing indirect calorimetry methods.